1. Field of the Invention
The present disclosure relates to a multiband antenna, and more particularly, to a multiband antenna for multiband operation and with a plurality of adjustable factors.
2. Description of the Prior Art
An antenna is utilized for transmitting or receiving radio frequency waves so as to communicate or exchange wireless signals. An electronic product with wireless communication functionality, such as a laptop and a personal digital assistant (PDA), usually accesses a wireless network through a built-in antenna. Therefore, to facilitate access to the wireless communication network, an ideal antenna should have a wide bandwidth and a small size to meet the trends of compact electronic products within a permissible range, so as to integrate the antenna into a portable wireless communication equipment. However, with advances in wireless communication technology, operating frequencies of different wireless communication systems may vary, and thereby, an ideal antenna should cover bandwidths required for different wireless communication networks with a single antenna.
For multiband applications in the prior art, a plurality of antennas or a plurality of radiation entities (e.g., slots in a slot antenna and branches in a dipole antenna) are commonly employed to respectively transmit and receive wireless signals of different frequency bands. Nevertheless, apart from complicating design further, the entire area of an antenna becomes larger as the required frequency bands increases. If the available space for the antennas is limited, interference may occur among the antennas, which significantly affects performance of the antennas. Therefore, providing an antenna of small size that allows multiband operation is a significant objective in the field.